Infrapatellar branch of the saphenous nerve lesion following tibial nailing: it is possible to avoid it?

BACKGROUND

Iatrogenic injury to the infrapatellar branches of saphenous nerve is a common complication following tibial nailing. This lesion seems to be directly related to the surgical approach adopted for nail insertion. The aim of the present study was to systematically review the current literature in order to assess the eventual superiority of one surgical approach for tibial nailing over the others in limiting the neurological impairment related to infrapatellar branch injury.

MATERIALS AND METHODS

The available literature was systematically screened searching papers dealing with iatrogenic injury to the infrapatellar branch of saphenous nerve after intramedullary tibial nailing. The terms "Saphenous" and "Infrapatellar branch" were used in combination with "intramedullary nailing" and "tibial fractures", supplying no limits regarding the publication year. Only publications in English were considered. Case reports, technical notes, instructional course, literature reviews, biomechanical and/ or in vitro studies were all excluded. Coleman methodological score was performed in all the retained articles.

RESULTS

Four articles matched the inclusion criteria. There were one original article and three retrospective study. Hypoesthesia and a larger extension of the area of sensory-loss were more frequently observed after vertical incision approach in three out of four articles. A trend towards a lower rate of iatrogenic nerve damage using a transverse incision was found in the remaining one, without any statistical significance.

CONCLUSIONS

In order to avoid infrapatellar nerve lesion, horizontal or oblique incisions or percutaneous approaches should be favored, although in some cases a longitudinal incision is required. Limited-extension incisions could minimize the risk and the incidence of this complication.

Infrapatellar Branch of the Saphenous Nerve: Therapeutic Approaches to Chronic Knee Pain

PURPOSE OF REVIEW

The infrapatellar branch of the saphenous nerve (IPS) is an under-investigated nerve that can be a source of chronic knee pain. This literature review aims to deliver an up-to-date review of chronic pain transmitted via the IPS along with therapeutic approaches available for pain refractory to conservative measures.

RECENT FINDINGS

Knee pain transmitted via the IPS can arise from several etiologies. Damage to the IPS is often iatrogenic and develops following total knee arthroplasty, anterior cruciate ligament reconstruction, and other knee surgical procedures. Other causes of IPS-derived pain include entrapment of the nerve, neuromas, Schwannomas, and pain from knee osteoarthritis transmitted through the IPS.This article investigated therapeutic approaches to pain derived from the IPS. Common approaches included radiofrequency ablation, neuroma excisions, Schwannoma excision, nerve blocks, surgical exploration, surgical release of an entrapped nerve, cryoablation, and peripheral nerve stimulation. Pain scores, duration of pain relief, adverse events, and secondary outcomes were all included in this review. A subset of the patient population experiences chronic pain deriving from the IPS that is refractory to conservative treatment measures. This review aims to evaluate the etiologies and therapeutic approaches for chronic pain arising from the IPS refractory to conservative treatments.

Distal subsartorial compartment block of the saphenous nerve - A dissection study and a patient case series

STUDY OBJECTIVE

A saphenous nerve block is an important tool for analgesia after foot and ankle surgery. The conventional midthigh approach to saphenous nerve block in the femoral triangle may impede ambulation by impairing quadriceps motor function.

PRIMARY OBJECTIVE

Developing a selective saphenous nerve block targeting the nerve distal to its emergence from the adductor canal in the subsartorial compartment.

DESIGN

This study consists of A) a dissection study and B) Data from a clinical case series.

SETTING

A) Medical University of Innsbruck, Austria (dissection of 15 cadaver sides) and. B) Aarhus University Hospital, Denmark (5 patients).

INTERVENTIONS

A) Five mL of methylene blue was injected into the subsartorial compartment distal to the intersection of the saphenous nerve and the tendon of the adductor magnus guided by ultrasound. B) Five patients undergoing major hindfoot and ankle surgery had a subsartorial compartment block with 10 mL of local anesthetic in addition to a popliteal sciatic nerve block.

MEASUREMENT

A) The frequencies of staining the saphenous and medial vastus nerves. B) Assessment of postoperative pain by NRS score (0-10) and success rate of saphenous nerve block by presence of cutaneous anesthesia in the anteromedial lower leg, and motor impairment by ability to ambulate.

MAIN RESULTS

A) The saphenous nerve was stained in 15/15 cadaver sides. A terminal branch of the medial vastus nerve was stained in 2/15 cadaver sides. B) All patients were fully able to ambulate without support. No patients had any post-surgical pain from the anteromedial aspect of the ankle and foot (NRS score 0). The success rate of saphenous nerve block was 100%.

CONCLUSION

The saphenous nerve can be targeted in the subsartorial compartment distal to the intersection of the nerve and the tendon of the adductor magnus. The subsartorial compartment block provided efficient analgesia without quadriceps motor impairment.

Femoral and obturator neuropathies

The femoral and obturator nerves both arise from the L2, L3, and L4 spinal nerve roots and descend into the pelvis before emerging in the lower limbs. The femoral nerve's primary function is knee extension and hip flexion, along with some sensory innervation to the leg. The obturator nerve's primary function is thigh adduction and sensory innervation to a small area of the medial thigh. Each may be injured by a variety of potential causes, many of them iatrogenic. Here, we review the anatomy of the femoral and obturator nerves and the clinical features and potential etiologies of femoral and obturator neuropathies. Their necessary investigations, including electrodiagnostic studies and imaging, their prognosis, and potential treatments, are discussed in this chapter.

Connection between medial dorsal cutaneous nerve and saphenous nerve: case report

PURPOSE

There are no data on the connection of the saphenous nerve (SN), located on the medial side of the foot, with the terminal branches of the superficial fibular nerve. The aim of this study is to reveal the variation that surgeons should pay attention to for anesthesia applied in foot surgeries.

METHODS

In this study, the left foot of a 70-year-old female cadaver fixed with formalin was dissected. The distance to the medial malleolus and the incision line was recorded using digital caliper to determine the reference points in the resulting variation.

RESULTS

It was observed that a branch from the SN, which arose from the SN and proceeded anteriorly to the upper part of the medial malleolus and continued towards the dorsum of the foot, hooked with a branch from the medial dorsal cutaneous nerve (MDCN). The branches arising from this hook were distributed on the medial edge of the foot up to the proximal metatarsophalangeal joint I. The distance of this nerve connection to the medial malleolus is 91.14 mm, and the distance to the incision line is 15.76 mm.

CONCLUSIONS

It is suggested that the case presented as an unusual SN variation, which may affect the success of local anesthesia in invasive procedures to the medial part of the foot and could be considered in the evaluation of sensory loss after anteromedial surgical approach to the ankle, should be included in the classification of the cutaneous innervation pattern of the foot.

Atypical Origin of the Saphenous Nerve and a Variation of the Right Iliacus Muscle: A Case Report

During a routine cadaveric dissection of the posterior abdominal wall, variations of the bilateral lumbar plexus and a variant saphenous nerve originating in the lower abdomen were noted and documented. The description of a saphenous nerve originating at the level of the lumbar plexus is, to the best of our knowledge, the first of its kind. Further study revealed more variations at the root of the lumbar plexus and bilateral branching patterns. A variant iliacus muscle entrapping the superior portion of the femoral nerve was also observed on the right side within the abdominal cavity. These variations are discussed in the context of risk of clinical intervention in this anatomical region..

Neuropathy Dermatitis: An Underdocumented Complication Following Total Knee Arthroplasty

Background

Midline surgical incision used in Total Knee Arthroplasty (TKA) is associated with iatrogenic injury to the infrapatellar branch of the saphenous nerve, which leads to neuropathic dermatitis around the healed surgical scar. There are very few studies with a limited number of cases that have reported this complication. We evaluated the incidence of neuropathic dermatitis and its implication for the functional outcome in TKA patients.

Methodology

Patients who underwent primary TKA between 1 January 2010 and 31 August 2019 and presented in follow-up with sensory disturbances and skin lesions adjacent to the surgical incision were evaluated in this study.

Results

A total of 3318 patients with 4282 TKAs were included, of which 188 patients presented with the clinical picture of neuropathic dermatitis. There were 136 females and 52 males with a mean age of 67.13 years (range 37-92 years). The mean duration from surgery to the appearance of skin lesions was 4.4 months (range 2-6 months), and they resolved at a mean duration of 7.67 (range 6-12) weeks. In our study, we found an incidence of 5.52%. All these patients had a stable and well-functioning knee at the time of presentation of the lesion with a mean Knee Society Score (KSS) of 92 (range 84-96).

Conclusion

In our study, we found the incidence of neuropathic dermatitis to be 5.52%, without any long-term implication on the functional outcome of operated knees. For a self-limiting complication of midline knee incision of TKA, it either resolves on its own or requires a short duration of topical steroid application.

Saphenous Nerve Schwannoma: A Rare Differential Diagnosis of Knee Pain in Children

Schwannomas are uncommon benign tumors of the peripheral nerves with a low risk of malignant transformation. They rarely affect children, can affect any part of the body but rarely occur in the lower extremity and typically present with a palpable mass, pain or neurological signs. Imaging helps to orient the diagnosis and anatomopathological examination helps to confirm it. We report a case of a 12-year-old girl who presented with left knee pain with subcutaneous mass overlying the tibial tuberosity medially. Clinical examination revealed a positive Tinel's sign. Magnetic resonance imaging (MRI) of the knee was performed, which revealed an encapsulated subcutaneous soft tissue mass overlying the tibial tuberosity medially, eccentric to the course of the infrapatellar branch of the saphenous nerve. The patient was operated with total intracapsular excision of the lesion and the anatomopathological study of the surgical specimen came back in favor of a schwannoma. Postoperatively, the patient showed a good recovery with disappearance of pain and swelling.

A case series

INTRODUCTION

Total knee arthroplasty (TKA) is a reliable and widespread solution for knee osteoarthritis treatment, but about 20% of the patients complains of persisting pain. Neuroma formation in the IPBSN (infrapatellar branch of the saphenous nerve) is an undervalued cause of persistent anterior pain after TKA. The aim of this study was to evaluate the effectiveness of the selective neuroma denervation on patients satisfaction and pain improvement.

MATHERIAL AND METHODS

Between 2014 and 2020, we evaluated 13 patients suffering from persistent anterior knee pain and numbness after TKA who underwent a surgical neurectomy of the IPBSN. After clinical assessment and diagnosis confirmation, we carried out the surgery. Short Form 12 Health (SF12), Oxford Knee Score (OKS), and Numeric Rating Scale (NRS) have been collected before and after the procedure. After the surgical treatment, the symptom's resolution and patients' satisfaction were attested by the achievement of the Minimal ClinicallyImportantDifference(MCID) of the self-administered patient-reported outcome measures (PROMs).

RESULTS

Our results showed a statistically significant improvement (p < 0.05) of patients pain perception (mean NRS improvement -4.2, SD 2.5) and overall satisfaction (with a mean increase in OKS of 14.5 points SD 9.4, and in SF12 of 6.5 points SD 4.0).

CONCLUSIONS

Hence, our study suggests that selective neuroma denervation may be an effective solution to improve the quality of life of patients who develop this complication after TKA.

Anatomical basis for ultrasound-guided infiltration of the saphenous nerve in the subsartorial canal

The present work is aimed studying the visibility and position of the vasto-adductor membrane with ultrasonography and demonstrating that injection performed under this membrane allows to infiltrate the saphenous nerve. It was analyzed with ultrasonography in four cadaveric subjects and in 13 volunteers. This membrane was clearly visible and methylene blue was located underneath it after injection in all cadaveric subjects. This study demonstrates that it can be used as a reliable anatomic landmark when performing an injection for both regional anesthesia and in the treatment of saphenous nerve tunnel syndrome.

Femoral nerve neuromonitoring for lateral lumbar interbody fusion surgery

BACKGROUND CONTEXT

The transpsoas lateral lumbar interbody fusion (LLIF) technique is an effective alternative to traditional anterior and posterior approaches to the lumbar spine; however, nerve injuries are the most reported postoperative complication. Commonly used strategies to avoid nerve injury (eg, limiting retraction duration) have not been effective in detecting or preventing femoral nerve injuries.

PURPOSE

To evaluate the efficacy of emerging intraoperative femoral nerve monitoring techniques and the importance of employing prompt surgical countermeasures when degraded femoral nerve function is detected.

STUDY DESIGN/SETTING

We present the results from a retrospective analysis of a multi-center study conducted over the course of 3 years.

PATIENT SAMPLE

One hundred and seventy-two lateral lumbar interbody fusion procedures were reviewed.

OUTCOME MEASURES

Intraoperative femoral nerve monitoring data was correlated to immediate postoperative neurologic examinations.

METHODS

Femoral nerve evoked potentials (FNEP) including saphenous nerve somatosensory evoked potentials (snSSEP) and motor evoked potentials with quadriceps recordings were used to detect evidence of degraded femoral nerve function during the time of surgical retraction.

RESULTS

In 89% (n=153) of the surgeries, there were no surgeon alerts as the FNEP response amplitudes remained relatively unchanged throughout the surgery (negative group). The positive group included 11% of the cases (n=19) where the surgeon was alerted to a deterioration of the FNEP amplitudes during surgical retraction. Prompt surgical countermeasures to an FNEP alert included loosening, adjusting, or removing surgical retraction, and/or requesting an increase in blood pressure from the anesthesiologist. All the cases where prompt surgical countermeasures were employed resulted in recovery of the degraded FNEP amplitudes and no postoperative femoral nerve injuries. In two cases, the surgeons were given verbal alerts of degraded FNEPs but did not employ prompt surgical countermeasures. In both cases, the degraded FNEP amplitudes did not recover by the time of surgical closure, and both patients exhibited postoperative signs of sensorimotor femoral nerve injury including anterior thigh numbness and weakened knee extension.

CONCLUSIONS

Multimodal femoral nerve monitoring can provide surgeons with a timely alert to hyperacute femoral nerve conduction failure, enabling prompt surgical countermeasures to be employed that can mitigate or avoid femoral nerve injury. Our data also suggests that the common strategy of limiting retraction duration may not be effective in preventing iatrogenic femoral nerve injuries.

Autonomic Denervation Dermatitis: A Relatively Undocumented 'ADD'itional Complication of Total Knee Replacements and Other Surgeries Around the Knee

BACKGROUND

Infrapatellar branch of the saphenous nerve lies subcutaneously and supplies the anterolateral aspect of knee below the patella. It is extremely susceptible to iatrogenic injuries during the surgeries around the knee, mainly total knee replacements (TKRs). Post operatively the patients present with localised area of numbness and in some instances a traumatic eczematous reaction termed autonomous denervation dermatitis (ADD) is witnessed, leading to skin manifestations that range from a simple rash to extensive lesions.

METHODOLOGY

A review of literature was conducted with search of relevant articles from Medline (PubMed), Embase, and Scopus which discussed eczematous skin lesions secondary to total knee replacements. Additionally, we noted studies which described these lesions in other surgeries around the knee like arthroscopies and fracture fixations.

RESULTS

Eight studies including atleast one case after TKR were reviewed. There was only one cohort study while the remaining included case reports and small case series. There were 69 cases of ADD appearing after TKR. The appearance of the skin lesions was lateral to the incision in 30/34 operated knees and on both sides of the incision in four knees after TKRs. Bilateral lesions were seen in only six patients of TKRs. There was no functional limitation caused by these lesions and they resolved either spontaneously or after using topical steroids.

CONCLUSION

ADD is a relatively uncommonly reported complication of TKRs, which can reduce patient satisfaction and increase surgeon apprehension. Although all cases of nerve damage do not manifest as cutaneous lesions, steps to minimise the damage to the nerve intra operatively should be taken. The diagnosis requires a high index of suspicion, and should not be dispelled as a simple allergic reaction without adequate investigations. Patients should be counselled to alleviate unnecessary fear and apprehensions.

Diagnostics of infrapatellar saphenous neuralgia-a reversible cause of chronic anteromedial pain following knee surgery

Objectives

To evaluate the impact of diagnostic nerve block and ultrasound findings on therapeutic choices and predict the outcome after concomitant surgery in patients with suspected neuropathy of the infrapatellar branch of the saphenous nerve (IPBSN).

Methods

Fifty-five patients following knee surgery with suspicion of IPBSN neuralgia were retrospectively included. Ultrasound reports were assessed for neuroma and postsurgical scarring (yes/no). Responders and non-responders were assigned following anesthetic injection of the IPBSN. The type of procedure (neurectomy/interventional pain procedure/other than nerve-associated therapy) and pain score at initial follow-up were recorded and patients were assigned as positive (full pain relief) or negative (partial/no pain relief) to therapeutic nerve treatment. Factors associated with a relevant visual analog scale (VAS) reduction were assessed using uni- and multivariate logistic regression models and chi-square for quantitative and qualitative variables (p ≤ 0.05).

Results

Responders (37/55) more often had an entrapment or an evident neuroma of the IPBSN (97% vs. 6%). A positive Hoffmann-Tinel sign (p = 0.002) and the absence of knee joint instability (p = 0.029) predicted a positive response of the diagnostic nerve block (90%; 26/29). In the follow-up after therapeutic nerve treatment, all patients with full pain relief showed neuromas or entrapment of the IPBSN. Patients negatively responding to therapeutic nerve treatment more frequently showed an additional knee joint instability (25% vs. 4%).

Conclusion

Selective denervation for neuropathic knee pain is beneficial in selected patients with significant VAS reduction after diagnostic nerve block. Non-responders following diagnostic nerve block but sonographic evidence of IPBSN pathologies need to be evaluated for other causes such as knee joint instability.

Key Points

• Sonographic diagnosis of neuroma or entrapment of the IPBSN is frequently seen in patients with anteromedial knee pain and leads to a good response to diagnostic nerve block following knee surgery.

• The vast majority of patients with clinical signs of IPBSN neuropathy and response to a diagnostic nerve block sustained full pain relief following therapeutic nerve treatment.

• Patients not responding to therapeutic IPBSN treatment have to be evaluated for other causes of anteromedial knee pain such as knee joint instability.

Management of chronic knee pain caused by postsurgical or posttraumatic neuroma of the infrapatellar branch of the saphenous nerve

PURPOSE

Injury to the infrapatellar branch of the saphenous nerve (IBSN) is a relatively common complication after knee surgery, which can interfere with patient satisfaction and functional outcome. In some cases, injury to the IBSN can lead to formation of a painful neuroma. The purpose of this study was to report the results of surgical treatment in a series of patients with IBSN painful neuroma.

METHODS

We retrospectively identified 37 patients who underwent resection of IBSN painful neuroma at our institution, after failure of non-operative treatment for a minimum of 6 months. Injury to the IBSN resulted from prior orthopedic surgery, vascular surgery, tumor resection, trauma, or infection. Leg pain and health-related quality of life were measured using the numeric rating scale (NRS) and EuroQol 5 dimensions (EQ-5D) questionnaire, respectively. Clinically meaningful improvement in leg pain was defined as reduction in NRS by at least 3 points. Predictors of favorable and unfavorable surgical outcome were investigated using multivariable logistic regression analysis.

RESULTS

Patient-reported leg pain, health-related quality of life, and overall satisfaction with the surgical outcome were obtained at 94 ± 52.9 months after neuroma surgery. Postoperative patient-reported outcomes were available for 25 patients (68% of the cohort), of whom 20 patients (80.0%) reported improvement in leg pain, 17 patients (68.0%) reported clinically meaningful improvement in leg pain, and 17 patients (68%) reported improvement in health-related quality of life. The average NRS pain score improved from 9.43 ± 1.34 to 5.12 ± 3.33 (p < 0.01) and the average EQ-5D functional score improved from 10.48 ± 2.33 to 7.84 ± 2.19 (p < 0.01). Overall patient reported satisfaction with the surgical outcome was good to excellent for 18 patients (72.0%). Older age, multiple prior orthopedic knee surgeries, and failed prior attempts to resect an IBSN neuroma were associated with non-favorable surgical outcome.

CONCLUSION

We conclude that surgical intervention is efficacious for appropriately selected patients suffering from IBSN painful neuroma.

Nonoperative treatment of recalcitrant neuritis of the infrapatellar saphenous nerve: a case series

Background

Neuritis of the infrapatellar branch of the saphenous nerve can result from iatrogenic injury, entrapment, bursitis, or patellar dislocation. Currently, there is an unmet clinical need for treating refractory neuritis nonsurgically.

Case presentation

Three patients presented with persistent anterior knee pain caused by neuritis of the infrapatellar branch of the saphenous nerve that had got excellent but only temporary relief from steroid and local anesthetic nerve block. The neuropathic pain diagnostic Douleur Neuropathique 4 questionnaire and painDETECT questionnaire confirmed presence of neuropathic pain. After injection with 25 mg amniotic and umbilical cord particulate, the patient’s pain decreased from 7.3 before injection to 0.3 at 6 weeks postinjection. In addition, neuropathic symptoms significantly improved at 2 weeks and were not present by 6 weeks. By 63 weeks, two of the patients reported continued complete pain relief, while one patient underwent total knee replacement due to an allergy of a previously implanted unicondylar implant.

Conclusions

This case series suggests that amniotic and umbilical cord particulate may be a viable alternative to reduce pain in patients with neuropathic pain.

Optimizing the methodology for saphenous nerve somatosensory evoked potentials for monitoring upper lumbar roots and femoral nerve during lumbar spine surgery: technical note

The demand for intraoperative monitoring (IOM) of lumbar spine surgeries has escalated to accommodate more challenging surgical approaches to prevent perioperative neurologic deficits. Identifying impending injury of individual lumbar roots can be done by assessing free-running EMG and by monitoring the integrity of sensory and motor fibers within the roots by eliciting somatosensory (SEP), and motor evoked potentials. However, the common nerves for eliciting lower limb SEP do not monitor the entire lumbar plexus, excluding fibers from L1 to L4 roots. We aimed to technically optimize the methodology for saphenous nerve SEP (Sap-SEP) proposed for monitoring upper lumbar roots in the operating room. In the first group, the saphenous nerve was consecutively stimulated in two different locations: proximal in the thigh and distal close to the tibia. In the second group, three different recording derivations (10-20 International system) to distal saphenous stimulation were tested. Distal stimulation yielded a higher Sap-SEP amplitude (mean ± SD) than proximal: 1.36 ± 0.9 µV versus 0.62 ± 0.6 µV, (p < 0.0001). Distal stimulation evoked either higher (73%) or similar (12%) Sap-SEP amplitude compared to proximal in most of the nerves. The recording derivation CPz-cCP showed the highest amplitude in 65% of the nerves, followed by CPz-Fz (24%). Distal stimulation for Sap-SEP has advantages over proximal stimulation, including simplicity, lack of movement and higher amplitude responses. The use of two derivations (CPz-cCP, CPz-Fz) optimizes Sap-SEP recording.

Anatomical variation of the saphenous nerve path: A case report

INTRODUCTION

The saphenous nerve has great importance on the sensitivity of the lower limb. In its normal course, it enters the adductor canal and travels under the sartorius muscle, on the medial side of the thigh.

METHODS

The anatomical variation was found accidentally during routine cadaveric dissection of the thigh at the Human Anatomy Laboratory of the Department of Morphophysiology of the Faculty of Medical Sciences of Minas Gerais (FCMMG).

RESULTS

A different pattern of path of the saphenous nerve was found, which appears to perforate the sartorius muscle.

DISCUSSION

Complaints of pain in the lower limbs are highly prevalent in the adult population. Saphenous neuropathy is a pathological entity that is associated with such a clinic and may have compression or trauma as its etiology. In the context of compression, it can be caused due to the unusual nerve path, as described in the present study. In trauma, knowledge of this variation is important to prevent iatrogenic damage to nervous tissue during surgical procedures.

CONCLUSION

The anatomic variation presented may be related to the symptom of pain in the lower limbs and is also relevant in the surgical context, in order to prevent complications.

Unusual case of the saphenous plexus in the thigh and why we should have borne this variation in mind

Detailed knowledge of the anatomy and different variations of the saphenous nerve could be of great importance not only to anatomists but also to clinicians. There are very few studies of saphenous nerve morphology in thigh. Most of the reported variations of this nerve concern the infrapatellar branch. In contrast, a saphenous plexus has been described in only one case. Herein, we present an unusual case of unilateral saphenous plexus formation in the right thigh found during routine anatomical dissection of a 69-year-old male Caucasian cadaver. We also present a brief discussion of the saphenous plexus and emphasize its potential clinical implications.

Frequency-Dependent Effects on Bladder Reflex by Saphenous Nerve Stimulation and a Possible Action Mechanism of Tibial Nerve Stimulation in Cats

Purpose

The present study determined the effects of saphenous nerve stimulation (SNS) at different stimulation frequencies on bladder reflex and explored a possible action mechanism of tibial nerve stimulation (TNS) on bladder activity in cats.

Methods

Two bipolar nerve cuff electrodes were implanted on the saphenous nerve and the contralateral tibial nerve in 13 cats, respectively. Multiple cystometrograms were obtained to determine the effects of single SNS at different frequencies and that of combined SNS and TNS on the micturition reflex by infusing normal saline.

Results

SNS at 1 Hz significantly reduced the bladder capacity (BC) to 59.8%±7.7% and 59.3%±5.8% of the control level at the intensity threshold (T) and 2T, respectively (P<0.05), while that at 20 Hz significantly increased the BC to 130.6%±4.2% of the control level at 6T (P<0.05). The TNS and SNS at 20 Hz did not significantly change the BCs at 1T (P>0.05), while combined stimulation at 1T significantly increased the BC to 122.7%±1.9% of the control level and induced an inhibitory effect which was similar to that TNS at 2T.

Conclusions

The current study revealed that SNS reduced and increased BC depending on different stimulation frequencies. The combined SNS and TNS maximized the clinical efficacy at a low intensity. Also, SNS may be a potential therapeutic mechanism of TNS.

Saphenous nerve injury after anterior cruciate ligament reconstruction: Reduced numbness area after ligamentoplasty using quadriceps tendon compared with hamstring tendon

PURPOSE

Injury to the infra-patellar branches of the saphenous nerve (IPBSN) is the main neurological complication of anterior cruciate ligament (ACL) reconstruction procedures. Surgical technique using quadriceps tendon (QT) autograft allows a less invasive tibial approach potentially protecting the IPBSN. The aim of this study was to compare the numbness surface of the cutaneous area supplied by the IPBSN after ACL reconstruction using either hamstring tendon (HT) or QT autografts.

METHODS

This was a retrospective comparative cohort study including 51 patients who underwent ACL reconstruction (27 QT and 24 HT) between January 2017 and April 2018. A sensory clinical evaluation was performed on each patient: length of the tibial scar, eventual numbness surface area and the type of sensory disorder were reported. To be considered as an IPBSN lesion, the numbness area had to spread at least one-centimeter away from the scar.

RESULTS

The average follow-up was 15 months. In the HT group, the numbness area surface measured 21.2 ± 19 cm² (0-77) and the scar length was on average 31.3 ± 5.6 mm. In the QT group, the numbness area was reduced to 5 ± 10 cm² (P = .0007) as well as the scar length (13.3 ± 2.8 mm, P < .0001). We counted five (17.8%) and 19 (76%) real IPBSN lesions in the QT and HT groups, respectively (P = .0002). Hypoesthesia was the main sensory disorder observed (87.5%).

CONCLUSION

Numbness area of the cutaneous surface supplied by the IPBSN after ACL reconstruction is reduced using QT autograft compared with HT autograft.

The anatomy of the saphenous and sural nerves as a source of processed nerve allografts

As an alternative to autologous nerve donors, acellular nerve allografts (ANAs) have been studied in many experiments. There have been numerous studies on processing ANAs and various studies on the clinical applications of ANA, but there have not been many studies on sources of ANAs. The purposes of the present study were to evaluate the course of the saphenous and sural nerves in human cadavers and help harvest auto- or allografts for clinical implications. Eighteen lower extremities of 16 fresh cadavers were dissected. For the saphenous nerve and sural nerve, the distances between each branch and the diameters at the midpoint between each branch were measured. In the saphenous nerve, the mean length between each branch ranged from 7.2 to 28.6 cm, and the midpoint diameter ranged from 1.4 to 3.2 mm. In the sural nerve, the mean length between each branch ranged from 17.4 to 21 cm, and the midpoint diameter ranged from 2.3 to 2.8 mm. The present study demonstrates the length of the saphenous and sural nerve without branches with diameters larger than 1 mm. With regard for the clinical implications of allografts, the harvest of a selective nerve length with a large enough diameter could be possible based on the data presented in the present study.

Lateral numbness in the lower leg: An underestimated complication following medial open-wedge high tibial osteotomy

BACKGROUND

This study aimed to investigate the incidence, degree, and natural course of lateral numbness following medial open-wedge high tibial osteotomy (MOWHTO). It also evaluated which predisposing factors would affect lateral numbness following MOWHTO.

METHODS

One-hundred and sixty-nine knees that underwent MOWHTO for treatment of varus osteoarthritis with a minimum follow-up of three years were enrolled. Lateral numbness in the lower leg was assessed with the light-touch method using a cotton wool ball and compared with the contralateral leg. Patients were classified into groups based on a scale according to grading of sensation to light touch. To assess the improvement of lateral numbness, lower leg sensation was investigated using a sensory score compared with the contralateral leg. The predisposing factors that would affect lateral numbness were assessed.

RESULTS

Lateral numbness was observed in 87 knees (51.5%) at six weeks postoperatively. Although 69 knees improved over time, 18 knees showed no improvement to the latest follow-up. The level of skin incision showed a significant association with lateral numbness on univariate and multivariate analyses: the higher the level of skin incision, the greater the degree of estimated numbness.

CONCLUSIONS

About half the patients reported postoperative lateral numbness in the lower leg following MOWHTO. Of the patients with lateral numbness, approximately one-fifth remained symptom until the last follow-up. The level of skin incision might be a risk factor for lateral numbness. Pre-operative patient education concerning the likelihood of lateral numbness is recommended.

LEVEL OF EVIDENCE

Level IV, case series.

Morphology of saphenous nerve in cadavers: a guide to saphenous block and surgical interventions

The knowledge about detailed morphology and relation of saphenous nerve is important to obtain successful saphenous nerve regional blocks to achieve pre- and post-operative anesthesia and analgesia, nerve entrapment treatments and to avoid damage of saphenous nerve during knee and ankle surgeries. The literature describing detailed morphology of saphenous nerve is very limited. We dissected 42 formalin fixed well embalmed cadaveric lower limbs to explore detailed anatomy, relation and mode of termination of saphenous nerve and measured the distances from the nearby palpable bony landmarks. The average distance of origin of saphenous nerve from inguinal crease was 7.89±1.42 cm, the distance from upper end of medial border of patella to saphenous nerve at that level was 8.11±0.85 cm, distance from tibial tuberosity was 7.53±0.98 cm and from midpoint of anterior border of medial malleolus was 0.45±0.14 cm. Saphenous nerve provided two infrapatellar branches at the level of mid to lower limit of patellar ligament in 90% cases. It was in close contact or adhered to great saphenous vein across the lower 2/3rd of leg lying either anterior, posterior or deep to the vein. The saphenous nerve terminated by bifurcating proximal to medial malleolus in majority of cases though no obvious bifurcation was observed in 9.52% cases. The detailed morphology, relations and the distances from palpable bony landmarks may be helpful for clinicians to achieve successful saphenous nerve block and to avoid saphenous nerve damage and related complications during orthopedic procedures.

No safe zone: The anatomy of the saphenous nerve and its posteromedial branches

BACKGROUND

Following a case of medial meniscal repair via an inside-out repair, a patient developed acute postoperative electric shock-like paresthesias of the proximal medial calf with any knee flexion beyond 80°. Open saphenous nerve exploration revealed entrapment by suture material of an unnamed branch off the sartorial branch of the saphenous nerve. Symptoms resolved immediately with release. The objective of the study was to perform a cadaveric study to examine the existence and frequency of these previously under-reported branches of the sartorial branch of the saphenous nerve.

METHODS

In 16 knees from eight fresh, matched whole cadavers, the medial structures of the knee were exposed, reproducible anatomical structures were identified, and previously under-described posteromedial branches of the sartorial nerve were identified and measured in relation to surrounding structures and the joint line.

RESULTS

The saphenous nerve, its sartorial and infrapatellar branches, and its posteromedial branches were identified in all specimens. The sartorial nerve divided from the saphenous nerve an average of 4.8 cm proximal to the medial femoral epicondyle. Between one and four further posteromedial branches off the sartorial nerve were identified. These branches formed at a range of 5.3 cm proximal to 3.0 cm distal to the joint line.

CONCLUSIONS

This cadaveric study establishes the consistent presence of a posteromedial branch off the sartorial nerve. It was consistently located near the posteromedial joint line. These branches are at risk for injury during medial meniscus repairs due to entrapment by suture materials, or during other surgical procedures near the posteromedial aspect of the knee.

Cadaveric study of the infrapatellar branch of the saphenous nerve: Can damage be prevented in total knee arthroplasty?

BACKGROUND

The infrapatellar branch of the saphenous nerve (IPBSN) is a purely sensory nerve innervating the anteromedial aspect of the knee and anteroinferior knee joint capsule. Total knee arthroplasty (TKA) is commonly used to treat end-stage arthritis, but the IPBSN is often injured and results in numbness around the anteromedial knee. The aim of this cadaveric study was to describe the course and variability of the IPBSN and to assess whether it is possible to preserve during a standard midline surgical approach in TKA.

METHODS

Ten fresh-frozen cadaver legs were dissected using a midline approach to the knee. Skin and subcutaneous flap were reflected to expose both the saphenous nerve and its branches. The branches of the IPBSN were identified, and their vertical distances above the tibial tuberosity (TB) were recorded: TB to inferior branch, to middle branch, and to superior branch.

RESULTS

There were 10 left-sided specimens (6 female, 4 male) with a mean age of 79.9 ± 9.8 years. 8 (80%) specimens had 2 branches of IPBSN while 2 (20%) specimens had 3 branches. The average distance from TB to the inferior branch was 16.8 ± 8.3 mm (3.0-28.0); middle branch, 24.0 ± 1.4 mm (23.0-24.9); and superior, 45.9 ± 7.7 mm (32.0-54.5).

CONCLUSION

Our cadaveric study found no consistent way to preserve the IPBSN using a standard midline approach in TKA. It is important to provide proper patient education on this complication, and surgeons should be aware of approximate locations and variations of IPBSN while performing other knee procedures.

Characterizing the transcutaneous electrical recruitment of lower leg afferents in healthy adults: implications for non-invasive treatment of overactive bladder

BACKGROUND

As a potential new treatment for overactive bladder (OAB), we investigated the feasibility of non-invasively activating multiple nerve targets in the lower leg.

METHODS

In healthy participants, surface electrical stimulation (frequency = 20 Hz, pulse width = 200 μs) was used to target the tibial nerve, saphenous nerve, medial plantar nerve, and lateral plantar nerve. At each location, the stimulation amplitude was increased to define the thresholds for evoking (1) cutaneous sensation, (2) target nerve recruitment and (3) maximum tolerance.

RESULTS

All participants were able to tolerate stimulation amplitudes that were 2.1 ± 0.2 (range = 2.0 to 2.4) times the threshold for activating the target nerve.

CONCLUSIONS

Non-invasive electrical stimulation can activate neural targets at levels that are consistent with evoking bladder-inhibitory reflex mechanisms. Further work is needed to test the clinical effects of stimulating one or more neural targets in OAB patients.

A finite element modeling study of peripheral nerve recruitment by percutaneous tibial nerve stimulation in the human lower leg

Percutaneous tibial nerve stimulation (PTNS) is a clinical therapy for treating overactive bladder (OAB), where an un-insulated stainless steel needle electrode is used to target electrically the tibial nerve (TN) in the lower leg. Recent studies in anesthetized animals not only confirm that bladder-inhibitory reflexes can be evoked by stimulating the TN, but this reflex can also be evoked by stimulating the adjacent saphenous nerve (SAFN). Although cadaver studies indicate that the TN and major SAFN branch(es) overlap at the location of stimulation, the extent to which SAFN branches are co-activated is unknown. In this study, we constructed a finite element model of the human lower leg and applied a numeric axon model (MRG model) to simulate the electrical recruitment of TN and SAFN fibers during PTNS. The model showed that up to 80% of SAFN fibers (located at the level of the needle electrode) can be co-activated when electrical pulses are applied at the TN activation threshold, the standard therapeutic amplitude. Both the location of the inserted electrode and stimulation amplitude were important variables that affected the recruitment of SAFN branches. This study suggests further work is needed to investigate the potential therapeutic effects of SAFN stimulation in OAB patients.

Injury to the Infrapatellar Branch of the Saphenous Nerve during ACL Reconstruction with Hamstring Tendon Autograft: A Comparison between Oblique and Vertical Incisions

BACKGROUND

Injury to the infrapatellar branch of the saphenous nerve (IPBSN) is common after arthroscopic ACL reconstruction with hamstring tendon autograft, as reported in up to 88% of the cases. Due to close relationship between the IPBSN with pes anserine tendons insertion skin incision may sever IPBSN while harvesting gracillis and semitendinous tendons. As the IPBSN course at the anterior of knee is oblique, we hypothesized a parallel skin incision with nerve passage may decrease nerve injury.

METHODS

Vertical and oblique incisions were compared in 79 patients in this clinical trial. The sensory loss area and patients' complain of numbness were measured at 2 and 8 weeks as well as 6 months after surgery.

RESULTS

Both the sensory loss area and patients' complain of numbness decreased significantly in the oblique incision group (P<0001).

CONCLUSION

According to our findings, oblique incision is suggested instead of traditional vertical incision when hamstring tendons are being harvested in arthroscopic ACL reconstruction with hamstring tendon autograft.Level of evidence: IV.

Nerve injury during anterior cruciate ligament reconstruction: A comparison between patellar and hamstring tendon grafts harvest

BACKGROUND

Tendon harvesting for anterior cruciate ligament reconstruction often injures sensory branches of the saphenous nerve. The reports on the prevalence of these injuries are scarce, while the implications on patient satisfaction are not known. Our objective was to compare the prevalence of sensory nerve injuries in patellar to hamstring autograft harvesting for anterior cruciate ligament reconstructions and follow up their postoperative course.

METHODS

Between 2012 and 2014, patients who had a primary anterior cruciate ligament reconstruction with bone patellar tendon bone or hamstring autografts were included (n=94). We evaluated and compared demographic details, level of activity and postoperative sensation disturbances between both groups. Data was analyzed retrospectively.

RESULTS

The mean postoperative follow-up time was 23months. At the last follow-up 46 (77%) patients of the patellar tendon group and 22 (58%) of the hamstring tendons group reported on reduced sensation; however, in both groups a quarter of these patients experienced full recovery within an average of seven to eight months. There were more patients in the hamstring tendons group that reported on partial recovery. In most cases midline incisions for patellar tendons harvesting injured the infrapatellar branch and medial incisions for hamstring tendons harvesting injured the sartorial branch of the saphenous nerve.

CONCLUSIONS

Harvesting tendon autografts for anterior cruciate ligament reconstructions by vertical incisions had high prevalence of saphenous nerve branches injury with a minor possibility for complete recovery within the first year. The loss of sensation was perceived by patients as a minor complication.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Femoral Nerve Block versus Adductor Canal Block for Analgesia after Total Knee Arthroplasty

Inadequate pain management after total knee arthroplasty (TKA) impedes recovery, increases the risk of postoperative complications, and results in patient dissatisfaction. Although the preemptive use of multimodal measures is currently considered the principle of pain management after TKA, no gold standard pain management protocol has been established. Peripheral nerve blocks have been used as part of a contemporary multimodal approach to pain control after TKA. Femoral nerve block (FNB) has excellent postoperative analgesia and is now a commonly used analgesic modality for TKA pain control. However, FNB leads to quadriceps muscle weakness, which impairs early mobilization and increases the risk of postoperative falls. In this context, emerging evidence suggests that adductor canal block (ACB) facilitates postoperative rehabilitation compared with FNB because it primarily provides a sensory nerve block with sparing of quadriceps strength. However, whether ACB is more appropriate for contemporary pain management after TKA remains controversial. The objective of this study was to review and summarize recent studies regarding practical issues for ACB and comparisons of analgesic efficacy and functional recovery between ACB and FNB in patients who have undergone TKA.

Technique, Efficiency and Safety of Different Nerve Blocks for Analgesia in Laser Ablation and Sclerotherapy for Lower Limb Superficial Venous Insufficiency - A Multicentre Experience

INTRODUCTION

Laser ablation and sclerotherapy, as minimally invasive alternatives to surgery for varicose veins, have good efficacy, safety and cosmetic result. Some form of anaesthesia is generally used for pain control.

AIM

To describe the technique and evaluate the efficacy and safety of femoral, saphenous and sciatic nerve blocks in isolation or in combination for analgesia during laser ablation and sclerotherapy for lower limb varicose veins.

MATERIALS AND METHODS

In this prospective observational study, over a period of 33 months, in 856 limbs of 681 patients with varicose veins, ultrasound guided femoral, saphenous and sciatic nerve blocks for analgesia were performed in 769, 808 and 52 instances respectively; following which, endovenous laser ablation, sclerotherapy or combination of both were carried out using standard practice. After completion of the procedure, Visual Analogue Pain Scale (VAS) was used for pain assessment, and muscle weakness was assessed clinically.

RESULTS

Nerve blocks could be successfully performed in all patients. Observed pain scores were 0 or 1 in 591 (69%), 2 or 3 in 214 (25%) and 4 in 51 (9%) legs with no score more than 4. Higher grades of pain were noted in femoral blocks during early stages of our learning curve. Mild to moderate muscle weakness was observed in 163 (2%) and 7 (13%) patients who underwent femoral and sciatic block respectively, which persisted for an average of two and a half hours and none beyond four and a half hours; saphenous nerve being a pure sensory nerve, did not cause motor weakness.

CONCLUSION

For analgesia during laser ablation and/or sclerotherapy of varicose veins, ultrasound guided nerve blocks can be easily and quickly performed. They provide excellent pain relief and comfort to the patient and to the operator; and they do not cause any additional complication.

Development and validation of a new method for locating patella sensory nerves for the treatment of inferior and superior knee pain

Background

Radiofrequency ablation and percutaneous cryoneurolysis to relieve knee pain requires treating large areas to ensure coverage due to high variability in the sensory innervation of the knee and limitations of current methods for defining treatment targets. This study sought to define and validate a new treatment approach targeting the major sensory nerves of the superior patella and expand upon previous work to define a more efficient treatment approach targeting the sensory nerves of the inferior patella.

Methods

Transcutaneous electrical nerve stimulation and ultrasound were used to evaluate the location and relationship of the cutaneous nerves to the superior and inferior aspects of the knee in 25 healthy volunteers. Using information derived from these evaluations, investigators defined new linear target treatment areas, or treatment lines, using anatomical landmarks, which were validated against locations of sensory nerves through cadaveric dissection of 15 fresh specimens.

Results

The proposed treatment lines captured the vast majority of nerve branching variations during cadaveric validation.

Conclusion

This study defined treatment lines, identifiable using only anatomical landmarks, which effectively target the nerves responsible for superior and inferior knee pain and reduce the total treatment area and procedure time when administering treatments such as radiofrequency ablation and cryoneurolysis.

TRPA1 insensitivity of human sural nerve axons after exposure to lidocaine

TRPA1 is an ion channel of the TRP family that is expressed in some sensory neurons. TRPA1 activity provokes sensory symptoms of peripheral neuropathy, such as pain and paraesthesia. We have used a grease gap method to record axonal membrane potential and evoked compound action potentials (ECAPs) in vitro from human sural nerves and studied the effects of mustard oil (MO), a selective activator of TRPA1. Surprisingly, we failed to demonstrate any depolarizing response to MO (50, 250 μM) in any human sural nerves. There was no effect of MO on the A wave of the ECAP, but the C wave was reduced at 250 μM. In rat saphenous nerve fibres MO (50, 250 μM) depolarized axons and reduced the C wave of the ECAP but had no effect on the A wave. By contrast, both human and rat nerves were depolarized by capsaicin (0.5 to 5 μM) or nicotine (50 to 200 μM). Capsaicin caused a profound reduction in C fibre conduction in both species but had no effect on the amplitude of the A component. Lidocaine (30 mM) depolarized rat saphenous nerves acutely, and when rat nerves were pretreated with 30 mM lidocaine to mimic the exposure of human nerves to local anaesthetic during surgery, the effects of MO were abolished whilst the effects of capsaicin were unchanged. This study demonstrates that the local anaesthetic lidocaine desensitizes TRPA1 ion channels and indicates that it may have additional mechanisms for treating neuropathic pain that endure beyond simple sodium channel blockade.

Neurofibromas of saphenous nerve mimicking thrombophlebitis

Young man aged 25 years complained of persistent pain on the medial side of the lower part of the thigh for 2 months. A cord like structure was palpable with 3 small nodular swelling parallel to the course of the long saphenous vein. Initially he was treated as a case of thrombophlebitis of saphenous vein in a clinic near his home. When the pain persisted after receiving injection heparin therapy, he was referred to the vascular surgery clinic. Duplex scan reported as thrombophlebitis of a vein parallel to the great saphenous vein. We continued the injection heparin and suspected thrombophilia. There were no other known risk factors for thrombosis. The pain persisted, so we excised the cord like structure with nodular swellings and biopsy reported it as neurofibromatosis of the saphenous nerve. Postoperatively the pain subsided dramatically and in the follow up clinic he mentioned about the paresthesias in the distribution area of saphenous nerve. Diagnosis of the small tumors of the peripheral nerves is difficult at this site and they can be easily mistaken for thrombophlebitis. Unusual pain and nodularity of the swelling as in this case can help us to consider early biopsy or excision of the tumor.